Tire with layer for retardation of air permeation

Abstract

The present invention relates to a pneumatic tire having a layer comprised of a starch/plasticizer composite for prevention, or retardation, of air permeation from its inner chamber into the remainder of the tire.

What is claimed is:  
     
       1. A pneumatic tire having an innerliner which comprises: 
       (i) a laminate comprised of a first layer positioned on and adhered to a diene-based rubber-based tire carcass surface comprised of (1) a butyl rubber composition or (b) a diene hydrocarbon-based rubber composition; and a second layer positioned on and adhered to an opposing surface of said first layer; wherein the second layer is a thin film of starch/plasticizer composite; wherein said first layer contains an adhesive agent for said starch/plasticizer composite; or  
       (ii) a starch/plasticizer composite/elastomer layer comprised of a blend of starch/plasticizer composite and dispersion therein of (a) a particulate diene-based rubber composition; wherein the content of said diene-based elastomer particles is from about 10 to about 60 weight percent of said blend, and (b) an adhesive agent for said starch/plasticizer;  
       wherein said starch/plasticizer composite is comprised of starch and plasticizer of a weight ratio in a range of about 0.4/1 to about 5/1; wherein said starch is composed of amylose units to amylopectin units in a ratio of about 15/85 to about 100/0, and has a softening point according to ASTM No. D 1228 in a range of about 180° C. to about 220° C.; and said starch/plasticizer composite has a softening point in a range of about 110° C. to about 170° C. according to ASTM No. D1228; and  
       wherein said adhesive agent has a moiety reactive with hydroxyl groups on the surface of the starch/plasticizer composite and another moiety interactive with said diene-based elastomer(s).  
     
     
       2. The tire of  claim 1  wherein said thin film of starch/plasticizer has a thickness within a range of about 0.05 to about 2 millimeters. 
     
     
       3. The tire of  claim 1  wherein said layer of starch/plasticizer/elastomer blend has a thickness within a range of about 1 to about 4 millimeters. 
     
     
       4. The tire of  claim 1  wherein said diene-based rubber of said tire carcass to which the aforesaid film, layer or laminate is adhered is comprised of at least one diene hydrocarbon-based elastomer in which at least 30 weight percent thereof is derived from a conjugated diene hydrocarbon. 
     
     
       5. The tire of  claim 1  wherein said adhesive is a compound of the general formula (I): 
       
         
           (OR) 3 —Si—R′—S n —R′—Si—(OR) 3   (I)  
         
       
       wherein “R” is an alkyl radical selected from at least one of methyl and ethyl radicals, “R′” is selected from at least one of methyl, ethyl, propyl and butyl radicals and “n” is a value from 2 to 8 with an average in a range of from 2 to 2.6 or from 3.5 to 4. 
     
     
       6. The tire of  claim 1  wherein said adhesive agent is a bis-(3-trialkoxysilylalkyl) polysulfide which contains an average of from 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge. 
     
     
       7. The tire of  claim 1  wherein said adhesive agent is a bis-(3-triethoxysilylpropyl) polysulfide having an average of from 2 to 2.5 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge. 
     
     
       8. The tire of  claim 1  wherein said starch of said starch/plasticizer composite is comprised of amylose units and amylopectin units in a ratio of about 15/85 to about 35/65 thereof. 
     
     
       9. The tire of  claim 1  wherein said plasticizer of said starch/plasticizer composite is a liquid at 23° C. and is selected from at least one of poly(ethylenevinyl alcohol), cellulose acetate and plasticizers based, at least in part, upon diesters of dibasic organic acids that form said starch/plasticizer composite having a softening point in a range of about 110° C. to about 160° C. when combined with said starch in a weight ratio of starch to plasticizer in a range of about 1/1 to about 3/1. 
     
     
       10. The tire of  claim 1  wherein said plasticizer of said starch/plasticizer has a softening point of less than the softening point of said starch and less than 160° C. and is selected from at least one of poly(ethylenevinyl alcohol), cellulose acetate and copolymers, and hydrolyzed copolymers, of ethylene-vinyl acetate copolymers having a vinyl acetate molar content of from about 5 to about 90 percent, ethylene-glycidal acrylate copolymers and ethylene-maleic anhydride copolymers. 
     
     
       11. The tire of  claim 1  wherein said plasticizer of said starch/plasticizer has a softening point of less than the softening point of said starch and less than 160° C. and is an ethylene-vinyl acelate copolymer having a vinyl acetate molar content within a range of from about 20 to about 60 percent. 
     
     
       12. The tire of  claim 1  wherein said film of starch/plasticizer is comprised of from one to and including three layers of such film; wherein the overall thickness of said layers of film is within a range of 0.15 to about 3 mm. 
     
     
       13. The tire of  claim 1  wherein said innerliner is said innerliner (i), prepared by adhering said film of starch/plasticizer composite to said diene-based rubber layer to form an laminate thereof followed by (a) adhering said laminate to the surface of said diene-based tire carcass rubber composition or (b) adhering said diene-based tire carcass rubber composition to said laminate, to form an assembly thereon and then vulcanizing the assembly to form an integral tire structure. 
     
     
       14. The tire of  claim 1  wherein said innerliner comprises a laminate comprised of a first layer positioned on and adhered to a diene-based rubber-based tire carcass surface comprised of (1) a butyl rubber composition or (b) a diene hydrocarbon-based rubber composition; and a second layer positioned on and adhered to an opposing surface of said first layer; wherein second layer is a thin film of starch/plasticizer composite; wherein said first layer contains an adhesive agent for said starch/plasticizer composite. 
     
     
       15. The tire of  claim 14  wherein said thin film has a thickness in a range of about 0.05 to about 2 mm and where said adhesive agent is a compound of the general formula (I): 
       
         
           (OR) 3 —Si—R′—S n —R′—/Si—(OR) 3   (I)  
         
       
       wherein “R” is an alkyl radical selected from at least one of methyl and ethyl radicals, “R′” is selected from at least one of methyl, ethyl, propyl and butyl radicals and “n” is a value from 2 to 8 with an average in a range of from 2 to 2.6 or from 3.5 to 4. 
     
     
       16. The tire of  claim 15  wherein said adhesive agent is a bis-(3-trialkoxysilylalkyl) polysulfide which contains an average of from 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge. 
     
     
       17. The tire of  claim 1  wherein said innerliner is comprised of a starch/plasticizer composite/elastomer layer comprised of a blend of starch/plasticizer composite and dispersion therein of (a) a particulate diene-based rubber composition; wherein the content of said diene-based elastomer particles is from about 10 to about 60 weight percent of said blend, and (b) an adhesive agent for said starch/plasticizer. 
     
     
       18. The tire of  claim 17  wherein said adhesive agent is a compound of the general formula (I): 
       
         
           (OR) 3 —Si—R′—S n —R′—Si—(OR) 3   (I)  
         
       
       wherein “R” is an alkyl radical selected from at least one of methyl and ethyl radicals, “R′” is selected from at least one of methyl, ethyl, propyl and butyl radicals and “n” is a value from 2 to 8 with an average in a range of from 2 to 2.6 or from 3.5 to 4. 
     
     
       19. The tire of  claim 17  wherein said adhesive agent is a bis-(3-trialkoxysilylalkyl) polysulfide which contains an average of from 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge.